Ontario Peak is one of several high peaks near Mount Baldy that are accessible by from Icehouse Saddle. Keep in mind that all distances and elevation change is in addition to that of the Icehouse Saddle via Icehouse Canyon hike.
From the saddle, the Ontario Peak Trail begins on a gently inclining path through lodgepole and sugar pine forest with views gradually opening up of the dominant Mount Baldy Summit to the northwest. The dusty paths and dramatic mountain views can make it easy to imagine that you're hiking somewhere in Yosemite National Park rather than just a short drive outside of the Los Angeles and Inland Empire metro areas.
About 1 mile in the trail reaches the backcountry Kelly Camp, a former resort nestled in a shady flat with a seasonal water spring. The route then climbs out of the trees and up the fire-scarred ridge, passing the fork to Bighorn Peak as it nears two false summits before traveling even further. Eventually the trail curves to reveal the craggy peak and the panoramic views of much of the Inland Empire along with the cascading slopes of the western San Gabriel Mountains and nearby Mount Baldy. Ontario Peak sits a lofty 3,800 feet above the Icehouse Canyon Trailhead. From here, it is about 2.75 miles to return to the Icehouse Saddle.